Punch & Shear Force
Punching and blanking force from cut perimeter, thickness, and shear strength, with stripping force, shear-angle relief, die clearance, and press load.
Perimeter, thickness,
shear strength.
One product, and the three things that change it in practice.
The force
F = L × t × τ: the length of the cut edge, the sheet thickness, and the material's shear strength. A round hole's perimeter is π × D; a rectangle's is 2 × (w + h); any other outline can be entered as a perimeter. Several identical holes punched together simply multiply. Stripping force — pulling the punch back out of the sheet — is added as a percentage (10–20 % is usual, 15 % by default).
Shear angle, clearance, and press load
Grinding a shear height h onto the punch spreads the cut over a longer stroke; the peak force drops to about F × t ÷ (t + h) while the energy stays the same. Die clearance per side is given as a percentage of thickness (8 % default; 5–10 % is typical for steel, more for hard alloys). Press load compares the total (peak + stripping) with the capacity you enter and warns above 80 % and 100 %.
Shear strengths, and what is not covered
The material list holds typical shear strengths from press-tool handbooks, not reviewed against a specific reference yet; alloy and temper move them by ±20 %, so a certificate value entered as custom is better. Not covered: punch buckling and tool life, fine blanking, nibbling overlap, or forming forces. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.